I presume you want to switch mostly for the ride harshness. I switched from Bridgestone RE050A Runflats to Michelin PS2 Runflats on my 550. The difference in ride Quality is huge, gone is the harshness and jaw busting jolts. The handling seems to be better in spirited driving. If I knew the improvement was so great , I would have done it long ago. But maybe this is a new generation, so it may not be the same tire it was a couple of years ago. Only downside is that they are expensive, but to me it was worth the additional cost. Too new to comment on wear.

I replace the Bridgestone run flats on my 2006 e90 330i with sport package. I picked the Dunlop Direzza Sport Z1 Star Spec based on specs. Some dealer feel that BMW wanted the vehicle to have runflats so keep them on the vehicle. I has been 1000 times better without them. My e90 now drives like my old e39 sports package. Good luck.

I presume you want to switch mostly for the ride harshness. I switched from Bridgestone RE050A Runflats to Michelin PS2 Runflats on my 550. The difference in ride Quality is huge, gone is the harshness and jaw busting jolts. The handling seems to be better in spirited driving. If I knew the improvement was so great , I would have done it long ago. But maybe this is a new generation, so it may not be the same tire it was a couple of years ago. Only downside is that they are expensive, but to me it was worth the additional cost. Too new to comment on wear.

I switched from Bridgestone RFT 050A's as well but to the Michelin PS2 Sport non-RFT's and added a BMW Mobility Kit for emergency situations.
The difference is huge! My Z4 ride is very comfortable, even on Chicago streets.

Same here on using PS2 ZPs on my E90 -- much better overall than the RE050A, more supple but excellent handling and outstanding ultimate grip. We did tear a sidewall in a rear one on a nasty spot along I-85 a while back though, so the BMW jack kit plus Griot's plug kit were useless. However, it did continue to roll along fine with no air and a 3" gash in the sidewall for about 5-6 miles until we got to convenient spot to buy used tire in Charlotte (one benefit of a RF if it is already dead or you don't care about it, you can drive carefully on it totally w/o air; however, if you plan to patch/plug it, make sure you catch it and stop as soon as the air pressure signal goes off so you don't degrade the sidewall).

My understanding is that the Mobility kit is basically a can of sealant in an aerosol can, correct?

Not an aerosol but a latex mixture poured into the tire through the valve stem. After pouring, the instructions tell you to roll the car forward so the tire completes a revolution, then use the supplied compressor to reinflate the tire.
Its the same kit the Z4M's are supplied with. I'd love to have a full sized spare but that's about all I'd have room for in my trunk......the price I pay for the roadster experience. If the RFT's are getting much better, maybe I'll try some in about 20K miles.

I too just changed from the OEM Bridgestone RFTs to the Michelin Zero Pressures and the difference is significant. The OEMs became downright dangerous at times after a few thousand miles, kicking the car out of the tramlining "gulley" into the next lane. The Roadster now rides like its supposed to (which is most likely still too tightly sprung for most people who want to have one 'cause they thinks its cute or whatever...buy an '09+ Z4 if you want a "comfort" setting Roadster!), but its no longer bone-jarring going over manhole covers at 35mph and while you still appropriately feel the payment, the tramlining doesn't throw you into the next lane on the hiway at 70mph. Now these are NOT soft tires (get non-ZPs and an M-Mobility kit is you want soft), but for my seat the ride is absolutely appropriate for the Roadster. I suspect on a 3er or 5er the ride is quite nice. I'd suggest looking into them; if you check the Tire Rack website reviews and forums (like bimmerfest), you'll find others saying the same thing about them.

I just got a flat on my Bridgestone RFs at just 15K. I will be getting a replacement RF on Monday, but not happy about it. My hubby won't let me pull all of them off and switch to non RFs. I hate the ride - not at all like my 02 325i - or the road noise.

Cars have come equipped with pneumatic (air-filled) tires for over a century, and aside from the inconvenience of having to change a flat, are nearly universally safe (Explorer Firestone scandal notwithstanding).

Has your husband given you a single valid reason not to allow the switch? If you have the technical ability to haul a tire from your trunk, onto the wheel hub, put the flat tire and wheel back in your trunk, AND handle the jacking procedure AND torque the lugnuts in the proper sequence to their proper torqueing spec, I don't see the problem.

Keeping your tires maintained and properly filled to ideal air pressure, rotating them (if applicable), air-filled tires are still perfectly viable alternatives, as many of your fellow members can attest to.

"Because I said you can't have them [regular tires]" is not a valid, rational reason to deny them to you.

That's a verbal communication problem, not a safety issue.

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I just got a flat on my Bridgestone RFs at just 15K. I will be getting a replacement RF on Monday, but not happy about it. My hubby won't let me pull all of them off and switch to non RFs. I hate the ride - not at all like my 02 325i - or the road noise.

Your hubby probably wants you enjoy the safety benefits of the Run Flats (opinions will vary as to their benefits, but personally, I think there are sufficient benefits). See if you can get him to spring for Michelin PS2 Zero Pressures; you just won't believe the difference in the ride from the Bridgestones; my much more tightly sprung Z4 is a different beast, er...car, with the Bridgestones gone. BMW puts the Michelins on many of their vehicles now (as well as Conti RFs). Maybe go to the dealer and see if you can find a 3er with Michelins ZPs and take it for a test drive to see the difference for yourself. Check out the endorsements and tests on this discussion of the Michelin ZPs.

When I bought the 330Ci (CPO at the end of 2008) it came with runflats (safe to assume the dealer had to put new tires on it and since they mostly stock runflats, that's what they mounted). I hated the damn things. The noise, way-too-stiff-for-stock ride and lackluster handling made me wonder what all the fuss about the ZHP package was. After I replaced them with regular performance tires, my car came alive. I now fully understand why everyone made such a fuss about it, it's night and day in every category compared to when it had the runflats.

I've also got runflats on our 535i and honestly they are absolute garbage. The ride is miserable, the noise level is too much for a "luxury" car and having already experienced the greatness that is having a spare tire (when one of the runflats shredded its sidewall, no amount of runflat technology was going to keep it on the road), I can honestly say that the replacement for the 535i will definitely NOT be a runflat equipped BMW. If BMW is unable to sell me a car with regular tires and a proper spare tire, then I'll shop somewhere else.

...If you have the technical ability to haul a tire from your trunk, onto the wheel hub, put the flat tire and wheel back in your trunk, AND handle the jacking procedure AND torque the lugnuts in the proper sequence to their proper torqueing spec, I don't see the problem.

Here are some: An '09 328i (her car) HAS no spare. Space-savers are hard to find if they can be fitted at all and a full-size wheel and tire will eat up most of the trunk. Cars equipped with run-flats are not factory-equipped with a jack. Or a lug wrench. Or a wheel chock. All these can be acquired as accessories but there goes more trunk space. Last, it takes more than technical ability to lift a 45lb wheel out of the trunk and mount it safely to the hub while the car is supported by a flimsy jack. That's a physical challenge for some people, regardless of gender.

Plus, if the last person to mount the wheel was a ham-fisted junior mechanic wielding an impact gun--not an uncommon occurrence--it may require literally inhuman strength (and/or a breaker bar) to break the lugs free, rendering all other arguments moot.

... air-filled tires are still perfectly viable alternatives ...

Run-flats are pneumatic tires, just stiff-sidewalled ones.

The aforementioned Michelin ZPs are getting great reviews and are only slightly pricier than the already-pricey Bridgestones. The tech is improving constantly and soon the difference will be negligible. The irony is, one reason for the convergence is the ridiculously low aspect ratios that pass for "normal" these days. Anyone who can't tell a run-flat from a conventional tire in a 60-series size, has probably lost all feeling in their gluteal region. They're much closer in a 35- or 40-series fitment--but in part, because that aspect ratio gives a pretty harsh baseline ride, period.

My Bridgestone RF Touranzas wore out early due to an alignment issue. I decided to go with RFs again mainly because it's a car that my daughter mostly drives. I did switch to Conti RFs at the recommendation of the folks at Tire Rack. They are a real improvement over the "Brickstones" but not much better if you hit a pothole, which are unavoidable here in New York.

My 335is came with Michelin PS2 ZPs. The ride is firm (more so than I would like) but certainly not harsh and not something I can't live with. On the other hand, I don't know whether a set of non-run flats would be more to my taste. I am considering changing to the Continental DW non-run flats and selling the Michelins, which I suspect will not be a problem, in light of the number of people who rave about them.

The other reason for changing is that if I ruin a tire the replacement will be a lot cheaper, and maybe even free because Continental includes a road hazard warrantee at no extra cost (through the Tire Rack). Of course, I would have the added expense of a donut spare or a mobility kit.

Any comments? I'm sitting on the fence waiting for my 335is to arrive in the US.